Inline desktop item with absolute t3code exec path

- Generate the desktop entry inside the derivation
- Point Exec at the installed binary via `${placeholder "out"}`

packages/t3code-desktop/default.nix

@@ -32,14 +32,6 @@
   pname = "t3code-desktop";
   version = desktopPackageJson.version;
 
-  desktopItem = makeDesktopItem {
-    name = "t3code";
-    desktopName = "T3 Code";
-    exec = "t3code %U";
-    icon = "t3code";
-    categories = ["Development"];
-    startupWMClass = "t3code";
-  };
 in
   stdenv.mkDerivation (finalAttrs: {
     inherit pname version;
@@ -95,7 +87,16 @@ in
       writableTmpDirAsHomeHook
     ];
 
-    desktopItems = [desktopItem];
+    desktopItems = [
+      (makeDesktopItem {
+        name = "t3code";
+        desktopName = "T3 Code";
+        exec = "${placeholder "out"}/bin/t3code %U";
+        icon = "t3code";
+        categories = ["Development"];
+        startupWMClass = "t3code";
+      })
+    ];
 
     env = {
       ELECTRON_SKIP_BINARY_DOWNLOAD = "1";